# An elephant has a mass of 156,000 kg and a volume of 6 kL. What is the elephant's density?

Jul 26, 2017

The numbers are not realistic! But see below....

#### Explanation:

Density is simply mass per unit volume.
Typical units are $g . c {m}^{-} 3$ or $k g . {m}^{-} 3$.

1 cubic metre is equivalent to 1000 litres, so units of "thousands of litres" (kl) and units of cubic metres are numerically identical.

So the mass is 156,000 kg, and the volume is 6 ${m}^{3}$

The density is therefore 156,000/6 = 26,000 $k g . {m}^{-} 3$

In reality, this is an unrealistic figure though. The density of water is 1000 $k g . {m}^{-} 3$ - a human being typically has density a bit lower, which is why we can swim in water. If an elephant had a density 26 times that of water it would sink like a stone whenever it went into a river! As a comparison, solid lead has a density of around 11,500 $k g . {m}^{-} 3$.

So whoever set you this question needs to use some slightly more realistic numbers, but you can see the methodology anyway.